German Society of Oto-Rhino-Laryngology, Head and Neck Surgery.
80th Annual Meeting of the German Society of Oto-Rhino-Laryngology, Head and Neck Surgery.
Rostock,
20.-24.05.2009.
DÃ¼sseldorf: German Medical Science GMS Publishing House; 2009. Doc09hno044

Outline

Cochleovestibulopathy may occur after stapedotomy and may lead to CT scanning to assess intravestibular intrusion depth of the stapes piston. The degree of accuracy of different modern CT scanners in this task has not been established. Stapes plasty was performed on 6 cadaver ears, and soft clip titanium pistons were inserted. Specimens were then scanned using three different scanners: Siemens Somatom Volume Zoom 64 (64-row scanner), Siemens Somatom Definition dual source 64-row scanner and flat-panel computed tomography (FD-CT). Piston length, width and intravestibular intrusion were measured by four independent observers (Figure 1 [Fig.Â 1]). Temporal bone dissection was then performed and vestibular piston intrusion measured microscopically. Piston dimensions was overestimated by all observers and CT scanners. Intravestibular penetration as assessed by computed tomography was consistently greater than the value found on cadaveric anatomic dissection. On average, the CT scan measurement of width was 0.176 mm greater, length 0.125 mm greater and intrusion 0.850 mm greater than the anatomic measurements. FD-CT showed better image quality and partly less bias in several measurements, but penetration depth was still variably overestimated.

We found that CT measurement consistently overstated intravestibular piston dimensions and vestibular intrusion. Modern temporal bone scanners are yet not able to depict the stapes piston position with a sufficient degree of accuracy.